Hank: Fish live without ever blinking. But virtually all land vertebrates do it, from salamanders to turtles to us. So scientists have set out to determine why blinking evolved and whether it was directly related to our move to land.

To figure out the likely origins of blinking, researchers started into the eyes of mudskippers, a little fish that weirdly spends a lot of time on land. And these charming amphibious fishes blink, but not the way we do. Mudskippers basically bloop their eyes down into their heads while a membrane simultaneously sweeps upward. Not only do they blink to avoid potential injury, a single blink clears their eyes of essentially all fine debris. Also, they blink to keep their eyes moist, likely spreading mucus secretions from their head over their eyes since they don't have tear glands. And if conditions get too dry, they adorably roll around in the water to spread it over their eyes.

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